<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
			function add(a,b=9){
				return a+b;
			}
			var r0=add(14);
			alert(r0);
			var r1=add(3,4);
			alert(r1);
			var r2=add("nihao"," js");
			alert(r2);
		</script>
	</head>
	<body>
	</body>
</html>
